In a liquid crystal display device, a classification based on an operating mode for liquid crystal molecules includes a phase change (PC) mode, a twisted nematic (TN) mode, a super twisted nematic (STN) mode, an electrically controlled birefringence (ECB) mode, an optically compensated bend (OCB) mode, an in-plane switching (IPS) mode, a vertical alignment (VA) mode, a fringe field switching (FFS) mode and a field induced photo-reactive alignment (FPA) mode. A classification based on a driving mode in the device includes a passive matrix (PM) and an active matrix (AM). The PM is classified into static and multiplex and so forth. The AM is classified into a thin film transistor (TFT), a metal insulator metal (MIM) and so forth.
A liquid crystal composition is sealed in the device. Physical properties required for the composition are different depending on the modes. Specific examples of the physical properties include stability to ultraviolet light and heat, a temperature range of a nematic phase, viscosity, optical anisotropy, dielectric anisotropy, specific resistance and an elastic constant. The composition is prepared by mixing many liquid crystal compounds. The physical properties required for the compound include a high stability to an environment such as water, air, heat and light, a wide temperature range of a liquid crystal phase, a small viscosity, a suitable optical anisotropy, a large (or small) dielectric anisotropy and a good compatibility with other compounds. The compound having a high maximum temperature of the nematic phase is preferred. The compound having a low minimum temperature in the liquid crystal phase such as the nematic phase and a smectic phase is preferred. The compound having a small viscosity contributes to the device having a short response time. A suitable value of optical anisotropy is different depending on a device mode. The compound having a large positive (or large negative) dielectric anisotropy is preferred for driving the device at low voltage. The compound having a small dielectric anisotropy is suitable for adjusting the viscosity, and so forth. The compound having a good compatibility with other compounds is preferred for preparing the composition. The device may be used at a temperature below a freezing point, and therefore the compound having a good compatibility at a low temperature is preferred.
A variety of liquid crystal compounds have so far been prepared. Development of a new liquid crystal compound is continued even now because excellent physical properties that are not found in conventional compounds are expected. The reason is that a suitable balance between two of physical properties required upon preparing the liquid crystal composition is expected for the new compound. Only a limited amount of examples of reports exist on the compound having a divalent group described below.

WO 1998/032721 A discloses compounds (141) to (160) and compounds (181) to (200) on pages 89 to 94. Examples of the compounds are as described below.

JP 2008-545671 A discloses a compound described below in paragraph 0074. The compound is a synthetic intermediate.
